Bulk acoustic wave notch resonator device and method of manufacturing the same

Abstract

The application provides a bulk acoustic wave ear-shaped channel resonator device and a manufacturing method thereof, and belongs to the technical field of semiconductors and microelectronics, and comprises a lower electrode layer, a lower electrode ear-shaped channel, an upper electrode layer, an upper electrode ear-shaped channel, a piezoelectric layer, a protective layer, a through hole, a supporting layer and a silicon substrate. The application solves the problems of large loss and low Q value of the bulk acoustic wave resonator in a non-longitudinal mode in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor and microelectronics technology, and particularly relates to a bulk acoustic wave ear-shaped channel resonator device and its manufacturing method. Background Technology

[0002] To reduce the cost and size of electronic devices, smaller filtering elements are needed, and thin-film bulk acoustic wave (BAS) resonators, as a novel type of filtering element, have the potential to meet these needs. A BAS resonator consists of a thin-film piezoelectric material sandwiched between two metal electrodes, forming a sandwich structure. This structure is suspended in air by a support layer surrounding it. When an electric field is generated between the two electrodes, the piezoelectric material converts some of the electrical energy into mechanical energy in the form of sound waves. These sound waves propagate longitudinally within the sandwich structure. Ideally, the energy is trapped in the longitudinal mode, but in reality, other non-longitudinal modes exist. These unwanted modes increase the losses of the BAS resonator and reduce its Q value. Summary of the Invention

[0003] To address the aforementioned shortcomings in the prior art, this invention provides a bulk acoustic wave ear-shaped channel resonator device and its manufacturing method, which solves the problems of high loss and low Q value of bulk acoustic wave resonators in non-longitudinal mode in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] This solution provides a bulk acoustic wave ear-shaped channel resonator device, including a lower electrode layer, a lower electrode ear-shaped channel, an upper electrode layer, an upper electrode ear-shaped channel, a piezoelectric layer, a protective layer, a through hole, a support layer, and a silicon substrate.

[0006] A piezoelectric layer is deposited on the upper electrode layer, a lower electrode layer is deposited on the piezoelectric layer, a protective layer is deposited on the lower electrode layer and the upper electrode layer, a support layer is deposited on the protective layer, the silicon substrate is located on the support layer, and the cavity formed by the silicon substrate, the support layer and the protective layer is a reflective air cavity on one side of the lower electrode layer.

[0007] The lower electrode layer is divided into two parts by the lower electrode ear-shaped channel: a first large-area resonator and a first small-area resonator skirt. The lower electrode ear-shaped channel consists of two first ear-shaped structures at both ends and a channel sandwiched between the two first ear-shaped structures. The two first ear-shaped structures have through holes penetrating the protective layer, the upper electrode layer, the piezoelectric layer, and the lower electrode layer. The upper electrode layer is divided into two parts by the upper electrode ear-shaped channel: a second large-area resonator and a second small-area resonator skirt. The upper electrode ear-shaped channel consists of two second ear-shaped structures at both ends and a channel sandwiched between the two second ear-shaped structures. The two second ear-shaped structures have through holes penetrating the protective layer, the upper electrode layer, the piezoelectric layer, and the lower electrode layer. The area enclosed by the lower electrode ear-shaped channel and the upper electrode ear-shaped channel is the usable area of ​​the bulk acoustic wave ear-shaped channel resonator.

[0008] The beneficial effects of the present invention are: the present invention reduces the non-longitudinal mode to a certain extent by setting a novel resonator device, thereby improving the Q value of the bulk acoustic wave resonator and solving the problems of high loss and low Q value of the bulk acoustic wave resonator in the non-longitudinal mode in the prior art.

[0009] Furthermore, the materials used for both the lower and upper electrode layers are at least one of molybdenum, copper, gold, tungsten, and / or ruthenium; the materials used for the piezoelectric layer are at least one of AlN, ScAlN, ZnO, and / or PZT; and the materials used for the support layer include SiN and / or SiO2.

[0010] Furthermore, the profile of the bulk acoustic wave ear-shaped channel resonator consists of at least N line segments and at least M circular arcs, where N is greater than or equal to 3 and M is greater than or equal to 2. Any two of the N line segments are not parallel. Of the M circular arcs, if M equals 2, the two arcs are part of the first and second ear-shaped structures, and the remaining line segments not connected to the arcs are connected. If M is greater than 2, the remaining arcs, except for those of the first and second ear-shaped structures, are positioned between two line segments and connect the two line segments.

[0011] The present invention also provides a method for manufacturing a bulk acoustic wave ear-shaped channel resonator device, comprising the following steps:

[0012] S1. Prepare a temporary silicon substrate;

[0013] S2. Deposit a seed layer on a temporary silicon substrate, wherein the seed layer is a single layer or a composite layer;

[0014] S3. Deposit an electrode layer on the seed layer;

[0015] S4. Deposit a sacrificial layer on the upper electrode layer through the via, and fill the sacrificial layer in the upper electrode ear-shaped channel of the upper electrode layer;

[0016] S5. Deposit a piezoelectric layer on the upper electrode layer;

[0017] S6. Deposit a sacrificial layer on the piezoelectric layer of the through-hole;

[0018] S7. Deposit a lower electrode layer on the piezoelectric layer;

[0019] S8. Deposit a sacrificial layer in the lower electrode layer through the via, and fill the sacrificial layer in the lower electrode ear-shaped channel of the lower electrode layer.

[0020] S9. Deposit a protective layer on the lower electrode layer;

[0021] S10. Deposit a support layer on the protective layer, wherein the support layer is a single-layer support layer or a composite-layer support layer;

[0022] S11. Cover the support layer with a silicon substrate, wherein the cavity formed by the silicon substrate, the support layer and the protective layer is a reflective air cavity on the side of the lower electrode layer.

[0023] S12. Flip the semi-finished product formed in step S11 by 180 degrees and etch away the temporary substrate and seed layer to expose the upper electrode layer.

[0024] S13. Deposit a protective layer on the upper electrode layer and adjust the thickness of the protective layer;

[0025] S14. Fill the protective layer of the through hole with a sacrificial layer;

[0026] S15. Inject etching liquid into the through hole to etch away the sacrificial layer and form the upper electrode ear-shaped channel and the lower electrode ear-shaped channel of the through hole.

[0027] The beneficial effects of the present invention are as follows: The novel resonator device manufactured by the above method reduces the non-longitudinal mode to a certain extent, thereby improving the Q value of the bulk acoustic wave resonator and solving the problems of high loss and low Q value of the bulk acoustic wave resonator in the non-longitudinal mode in the prior art. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the layered structure of the ear-shaped channel section of this device.

[0029] Figure 2 This is a schematic diagram of the layered structure of another ear-shaped channel portion of the device in this embodiment.

[0030] Figure 3 This is a flowchart of the manufacturing method of the present invention.

[0031] Figure 4 This is a schematic diagram of preparing a temporary silicon substrate in this embodiment.

[0032] Figure 5This is a schematic diagram of a seed layer being deposited on a temporary silicon substrate in this embodiment.

[0033] Figure 6 This is a schematic diagram of the deposition of the upper electrode layer on the seed layer in this embodiment.

[0034] Figure 7 This is a schematic diagram of the deposition of a sacrificial layer on the upper electrode layer and the filling of the sacrificial layer on the ear-shaped channel of the upper electrode in this embodiment.

[0035] Figure 8 This is a schematic diagram of the piezoelectric layer deposited on the upper electrode layer in this embodiment.

[0036] Figure 9 This is a schematic diagram of the deposition of a sacrificial layer on the piezoelectric layer in this embodiment.

[0037] Figure 10 This is a schematic diagram of the deposition of an electrode layer on the piezoelectric layer in this embodiment.

[0038] Figure 11 This is a schematic diagram of the deposition of a sacrificial layer in the lower electrode layer and the filling of the sacrificial layer in the ear-shaped channel of the lower electrode in this embodiment.

[0039] Figure 12 This is a schematic diagram of the protective layer deposited on the lower electrode layer in this embodiment.

[0040] Figure 13 This is a schematic diagram of the support layer deposited on the protective layer in this embodiment.

[0041] Figure 14 This is a schematic diagram of the substrate covering the support layer and the cavity formed in this embodiment.

[0042] Figure 15 This is a schematic diagram showing the exposed upper electrode layer in this embodiment.

[0043] Figure 16 This is a schematic diagram of the protective layer deposited on the upper electrode in this embodiment.

[0044] Figure 17 This is a schematic diagram of filling the protective layer with a sacrificial layer in this embodiment.

[0045] Figure 18 This is a schematic diagram showing the formation of the through hole, the upper electrode ear-shaped channel, and the lower electrode ear-shaped channel in this embodiment.

[0046] Wherein, 1-lower electrode layer, 101-first large-area resonator, 102-first small-area resonator skirt, 2-lower electrode ear-shaped channel, 3-upper electrode layer, 301-second large-area resonator, 302-second small-area resonator skirt, 4-upper electrode ear-shaped channel, 5-piezoelectric layer, 6-protective layer, 7-through hole, 8-support layer, 9-silicon substrate, 10-temporary silicon substrate, 11-seed layer, 12-reflective air cavity, 13-area. Detailed Implementation

[0047] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0048] Example 1

[0049] like Figure 1 As shown, the present invention provides a bulk acoustic wave ear-shaped channel resonator device, including a lower electrode layer 1, a lower electrode ear-shaped channel 2, an upper electrode layer 3, an upper electrode ear-shaped channel 4, a piezoelectric layer 5, a protective layer 6, a through hole 7, a support layer 8, and a silicon substrate 9.

[0050] A piezoelectric layer 5 is deposited on the upper electrode layer 3, a lower electrode layer 1 is deposited on the piezoelectric layer 5, a protective layer 6 is deposited on the lower electrode layer 1 and the upper electrode layer 3, a support layer 8 is deposited on the protective layer 6, a silicon substrate 9 is located on the support layer 8, and the cavity formed by the silicon substrate 9, the support layer 8 and the protective layer 6 is a reflective air cavity on one side of the lower electrode layer 1.

[0051] The lower electrode layer 1 is divided into two parts by the lower electrode ear-shaped channel 2: a first large-area resonator 101 and a first small-area resonator skirt 102. The lower electrode ear-shaped channel 2 consists of two first ear-shaped structures at both ends and a channel sandwiched between the two first ear-shaped structures. The two first ear-shaped structures have through holes 7 that penetrate the protective layer 6, the upper electrode layer 3, the piezoelectric layer 5, and the lower electrode layer 1. The upper electrode layer 3 is divided into two parts by the upper electrode ear-shaped channel 4: a second large-area resonator 301 and a second small-area resonator skirt 302. The upper electrode ear-shaped channel 4 consists of two second ear-shaped structures at both ends and a channel sandwiched between the two second ear-shaped structures. The two second ear-shaped structures have through holes 7 that penetrate the protective layer 6, the upper electrode layer 3, the piezoelectric layer 5, and the lower electrode layer 1. The area enclosed by the lower electrode ear-shaped channel 2 and the upper electrode ear-shaped channel 4 is the usable area of ​​the bulk acoustic wave ear-shaped channel resonator.

[0052] In this embodiment, the contour of the bulk acoustic wave ear-shaped channel resonator consists of at least N line segments and at least M arcs, where N is greater than or equal to 3 and M is greater than or equal to 2. Any two of the N line segments are not parallel. Of the M arcs, if M equals 2, the two arcs are part of the first and second ear-shaped structures. The remaining line segments not connected to the arcs are connected. For example, if there are 6 line segments and 2 arcs, one arc corresponds to two line segments, and the two arcs correspond to 4 line segments. Then, 2-3 line segments are not connected to the arcs and will be directly connected. If there are more than 2 arcs, besides the two ear-shaped arcs, the remaining arcs will be sandwiched between the line segments, connecting them. If M is greater than 2, besides the arcs of the first and second ear-shaped structures, the remaining arcs are positioned between two line segments, connecting them.

[0053] In this embodiment, the materials used for both the lower electrode layer 1 and the upper electrode layer 3 are at least one of molybdenum, copper, gold, tungsten and / or ruthenium, the materials used for the piezoelectric layer 5 are at least one of AlN, ScAlN, ZnO and / or PZT, and the materials used for the support layer include SiN and / or SiO2.

[0054] In this embodiment, as Figure 1 As shown, Figure 1 middle Figure 1 (a) is a schematic diagram including the upper and lower electrode layers, the upper and lower electrode ear-shaped structure, and the through holes in the ear-shaped structure. Figure 1 (b) is a schematic diagram including the lower electrode layer, the lower electrode ear-shaped structure, and the through hole in the first ear-shaped structure. Figure 1 (c) is a schematic diagram including the upper electrode layer, the upper electrode ear-shaped structure, and the through holes in the second ear-shaped structure. Figure 1(d) is a schematic diagram including upper and lower electrode ear-shaped structures and through holes in the ear-shaped structures. The lower electrode layer 1 is made of metals such as molybdenum, tungsten, and copper. The lower electrode layer 1 is divided into two parts by the lower electrode ear-shaped channel 2: a first large-area resonator 101 and a first small-area resonator skirt 102. The lower electrode ear-shaped channel 2 consists of two first ear-shaped structures at both ends and a channel sandwiched between the two first ear-shaped structures. The two first ear-shaped structures have through holes 7 penetrating the protective layer 6, the upper electrode layer 3, the piezoelectric layer 5, and the lower electrode layer 1. The upper electrode layer 3 is made of metals such as molybdenum, tungsten, and copper. The upper electrode layer 3 is divided into two parts by the upper electrode ear-shaped channel 4: a second large-area resonator 301 and a second small-area resonator skirt 302. The upper electrode ear-shaped channel 4 consists of two second ear-shaped structures at both ends and a channel sandwiched between the two second ear-shaped structures. The two second ear-shaped structures have through holes 7 penetrating the protective layer 6, the upper electrode layer 3, the piezoelectric layer 6, and the lower electrode layer 1. The area 13 enclosed by the lower electrode ear-shaped channel 2 and the upper electrode ear-shaped channel 4 is the actual usable area of ​​the resonator. In this embodiment, the profile of the bulk acoustic wave ear-shaped channel resonator consists of at least three line segments and at least two arcs, wherein any two line segments are not parallel; in this embodiment, the profile of the bulk acoustic wave ear-shaped channel resonator consists of six line segments and six arcs, wherein two arcs are part of the ear-shaped structure, and the remaining arcs are placed in the middle of any two other line segments, connecting the two line segments. Figure 1 In (b), in addition to the four line segments connected to the ear-shaped structure, there are two vertical line segments (line segments not connected to the arc). The connection between these two vertical line segments and other line segments is through small arcs other than the ear-shaped arc, for a total of four small arcs.

[0055] In this embodiment, as Figure 2 As shown, Figure 2 middle Figure 2 (a) is a schematic diagram including the upper and lower electrode layers, the upper and lower electrode ear-shaped structure, and the through holes in the ear-shaped structure. Figure 2 (b) is a schematic diagram including the lower electrode layer, the lower electrode ear-shaped structure, and the through hole in the first ear-shaped structure. Figure 2 (c) is a schematic diagram of the through holes in the upper electrode layer, the upper electrode ear-shaped structure, and the second ear-shaped structure. Figure 2 (d) is a schematic diagram including the upper and lower electrode ear-shaped structure and the through hole in the ear-shaped structure. The profile of the bulk acoustic wave ear-shaped channel resonator in this embodiment consists of 6 line segments and 2 arcs. These two arcs are part of the arc segments of the ear-shaped structure. When the number of arcs is equal to 2, the arcs can only be part of the arc segments of the ear-shaped structure. When it is greater than 2, in addition to the two part arc segments of the ear-shaped structure, the remaining arcs can be set between the other two straight line segments.

[0056] In this embodiment, the device includes a piezoelectric layer 5 and its upper and lower metal layers (upper electrode layer 3 and lower electrode layer 1). The upper electrode layer 3 is divided into two parts by the upper electrode ear-shaped channel 4: a second large-area resonator 301 and a second small-area resonator skirt 302. The second large-area resonator 301 actually plays a resonant and connecting role, while the skirt of the second small-area resonator 302 plays a connecting and supporting role. The lower electrode layer 1 is divided into a first large-area resonator 101 and a first small-area resonator by the lower electrode ear-shaped channel 2. The skirt 102 consists of two parts. The part of the first large-area resonator 101 actually serves as the resonator and connection, while the skirt of the first small-area resonator 102 serves as the connection and support. The ear-shaped channel consists of two ear-shaped structures at both ends and a channel in the middle. The ear-shaped structure has a through hole 7, which penetrates the protective layer 6, the upper electrode layer 3, the piezoelectric layer 5, and the lower electrode layer 1. By injecting etching liquid into the through hole 7, the etching liquid etches away the filling sacrificial layer along the upper electrode ear-shaped channel 4 and the lower electrode ear-shaped channel 2. The area 13 enclosed by the upper and lower ear-shaped channels (upper electrode ear-shaped channel 4 and lower electrode ear-shaped channel 2) is the actual usable area of ​​the ear-shaped channel resonator. The bulk acoustic wave ear-shaped channel resonator profile consists of at least three line segments and at least two circular arcs, where any two line segments are not parallel. When the number of arcs is equal to two, the arcs can only be a portion of the ear-shaped structure. When the number is greater than two, in addition to the two portion arcs of the ear-shaped structure, the remaining arcs can be placed between the other two straight line segments. This novel resonator reduces non-longitudinal modes to some extent, thereby improving the Q value of the bulk acoustic wave resonator.

[0057] Example 2

[0058] like Figure 3 As shown, the present invention provides a method for manufacturing a bulk acoustic wave ear-shaped channel resonator device, comprising the following steps:

[0059] S1, such as Figure 4 As shown, a temporary silicon substrate 10 is prepared;

[0060] S2, such as Figure 5 As shown, a seed layer 11 is deposited on a temporary silicon substrate 10, wherein the seed layer 11 is AlN, or it can be a composite layer composed of AlN, SiO2, etc.

[0061] S3, such as Figure 6 As shown, an upper electrode layer 3 is deposited on the seed layer 11. The material of the upper electrode layer 3 is a metal such as molybdenum, tungsten, or copper.

[0062] S4, such as Figure 7 As shown, a sacrificial layer is deposited on the upper electrode layer 3 through the through hole 7, and a sacrificial layer is filled in the upper electrode ear-shaped channel 4 of the upper electrode layer 3.

[0063] S5, such asFigure 8 As shown, a piezoelectric layer 5 is deposited on the upper electrode layer 3. The piezoelectric layer 5 can be a piezoelectric material such as AlN, ScAlN doped with various scandium element concentrations, or PTZ.

[0064] S6, such as Figure 9 As shown, a sacrificial layer is deposited on the piezoelectric layer 5 through the via 7;

[0065] S7, such as Figure 10 As shown, an electrode layer 1 is deposited on the piezoelectric layer 5; the electrode layer 1 is made of metals such as molybdenum, tungsten, and copper.

[0066] S8, such as Figure 11 As shown, a sacrificial layer is deposited in the lower electrode layer 1 through the through-hole 7, and a sacrificial layer is filled in the lower electrode ear-shaped channel 2 of the lower electrode layer 1.

[0067] S9, such as Figure 12 As shown, a protective layer 6 is deposited on the lower electrode layer 1; the material of the protective layer is AlN, etc.

[0068] S10, such as Figure 13 As shown, a support layer 8 is deposited on the protective layer 6, wherein the support layer 8 is a single support layer of SiO2, AlN and SiN or a composite layer composed of these three materials.

[0069] S11, such as Figure 14 As shown, a silicon substrate 9 is placed on the support layer 8. The cavity formed by the silicon substrate 9, the support layer 8, and the protective layer 6 is a reflective air cavity 12 on one side of the lower electrode layer 1, which can effectively reflect energy back, thereby confining the energy and improving the Q value of the resonator.

[0070] S12, such as Figure 15 As shown, the semi-finished product formed in step S11 is flipped 180 degrees and the temporary substrate 10 and seed layer 11 are etched away to expose the upper electrode layer 3.

[0071] S13, such as Figure 16 As shown, a protective layer 6 is deposited on the upper electrode layer 3, and the thickness of the protective layer 6 is adjusted to adjust the frequency of the resonator to the required position; the material of the protective layer 6 is AlN, etc.

[0072] S14, such as Figure 17 As shown, a sacrificial layer is filled on the protective layer 6 through the through hole 7;

[0073] S15, such as Figure 18 As shown, etching liquid is injected into the through hole 7 to etch away the sacrificial layer, forming the upper electrode ear-shaped channel 4 and the lower electrode ear-shaped channel 2 of the through hole 7.

[0074] Through the above design, this invention solves the problems of high loss and low Q value of bulk acoustic resonators in non-longitudinal mode in the prior art.

Claims

1. A bulk acoustic wave ear-shaped channel resonator device, characterized in that, It includes a lower electrode layer (1), a lower electrode ear-shaped channel (2), an upper electrode layer (3), an upper electrode ear-shaped channel (4), a piezoelectric layer (5), a protective layer (6), a through hole (7), a support layer (8), and a silicon substrate (9); A piezoelectric layer (5) is deposited on the upper electrode layer (3), a lower electrode layer (1) is deposited on the piezoelectric layer (5), a protective layer (6) is deposited on the lower electrode layer (1) and the upper electrode layer (3), a support layer (8) is deposited on the protective layer (6), the silicon substrate (9) is located on the support layer (8), and the cavity formed by the silicon substrate (9), the support layer (8) and the protective layer (6) is a reflective air cavity on one side of the lower electrode layer (1); The lower electrode layer (1) is divided into two parts by the lower electrode ear-shaped channel (2): a first large-area resonator (101) and a first small-area resonator skirt (102). The lower electrode ear-shaped channel (2) consists of two first ear-shaped structures at both ends and a channel sandwiched between the two first ear-shaped structures. The two first ear-shaped structures are provided with a through-hole (7) of the protective layer (6), the upper electrode layer (3), the piezoelectric layer (5), and the lower electrode layer (1). The upper electrode layer (3) is divided into two parts by the upper electrode ear-shaped channel (4). The upper electrode ear-shaped channel (4) consists of two parts: the second large-area resonator (301) and the second small-area resonator skirt (302). The upper electrode ear-shaped channel (4) is composed of two second ear-shaped structures at both ends and a channel sandwiched between the two second ear-shaped structures. The two second ear-shaped structures are provided with through holes (7) that penetrate the protective layer (6), the upper electrode layer (3), the piezoelectric layer (5), and the lower electrode layer (1). The area enclosed by the lower electrode ear-shaped channel (2) and the upper electrode ear-shaped channel (4) is the usable area of ​​the bulk acoustic wave ear-shaped channel resonator.

2. The bulk acoustic wave ear-shaped channel resonator device according to claim 1, characterized in that, The materials used for the lower electrode layer (1) and the upper electrode layer (3) are at least one of molybdenum, copper, gold, tungsten and / or ruthenium, the materials used for the piezoelectric layer (5) are at least one of AlN, ScAlN, ZnO and / or PZT, and the materials used for the support layer include SiN and / or SiO2.

3. The bulk acoustic wave ear-shaped channel resonator device according to claim 2, characterized in that, The profile of the bulk acoustic wave ear-shaped channel resonator consists of at least N line segments and at least M arcs, where N is greater than or equal to 3 and M is greater than or equal to 2. Any two of the N line segments are not parallel. Of the M arcs, if M equals 2, the two arcs are part of the first and second ear-shaped structures, and the remaining line segments not connected to the arcs are connected. If M is greater than 2, the remaining arcs, except for those of the first and second ear-shaped structures, are positioned between two line segments and connect the two line segments.

4. A method for manufacturing a bulk acoustic wave ear-shaped channel resonator device as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Prepare a temporary silicon substrate (10). S2. Deposit a seed layer (11) on a temporary silicon substrate (10), wherein the seed layer (11) is a single layer or a composite layer of SiO2; S3. Deposit an upper electrode layer (3) on the seed layer (11). S4. A sacrificial layer is deposited on the upper electrode layer (3) through the through hole (7), and a sacrificial layer is filled in the upper electrode ear-shaped channel (4) of the upper electrode layer (3); S5. Deposit a piezoelectric layer (5) on the upper electrode layer (3); S6. Deposit a sacrificial layer on the piezoelectric layer (5) through the through hole (7); S7. Deposit a lower electrode layer (1) on the piezoelectric layer (5); S8. A sacrificial layer is deposited in the lower electrode layer (1) through the through hole (7), and a sacrificial layer is filled in the lower electrode ear-shaped channel (2) of the lower electrode layer (1). S9. Deposit a protective layer (6) on the lower electrode layer (1). S10. Deposit a support layer (8) on the protective layer (6), wherein the support layer (8) is a single-layer support layer or a composite layer support layer; S11. Cover the support layer (8) with a silicon substrate (9), wherein the cavity formed by the silicon substrate (9), the support layer (8) and the protective layer (6) is a reflective air cavity on one side of the lower electrode layer (1). S12. Flip the semi-finished product formed in step S11 by 180 degrees and etch away the temporary substrate (10) and seed layer (11) to expose the upper electrode layer (3). S13. Deposit a protective layer (6) on the upper electrode layer (3) and adjust the thickness of the protective layer (6); S14. Fill the protective layer (6) of the through hole (7) with a sacrificial layer; S15. Etching liquid is injected into the through hole (7) to etch away the sacrificial layer and form the upper electrode ear-shaped channel (4) and the lower electrode ear-shaped channel (2) of the through hole (7).

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